This invention pertains to anti-vibration spacers formed of shape memory metals (SMM), and adapted for vibration dampening for elongated tubes in tubular type heat exchangers operating at various temperature levels.
For tubular type heat exchangers containing elongated tube bundles, undesired vibration of the tubes which are not adequately supported can occur during operations. Such undesired vibration can be self-induced by flowing fluids circulating at high velocities in or past the tubes, or such vibrations can occur because the heat exchangers are located near reciprocating or rotating machinery such as compressors and pumps which induce the vibrations. Such tube vibration can cause metal fatigue and tube failures, which can result in undesired plant outages and expensive repairs.
The general use of expandable type anti-vibration spacer bars in tubular type steam generators is known, having been disclosed in U.S. Pat. No. 4,653,576 to Legally. Such expandable anti-vibration bars are positioned between columns of tubes in a steam generator and utilize relative movement between mating bar halves to increase overall thickness of the bars by suitable mechanical take-up means. U.S. Pat. No. 4,789,028 to Gowda et al discloses pressurizable anti-vibration bars used between adjacent rows of tubes in tube bundles carrying a high temperature coolant in a steam generator, which bars increase in width upon being pressurized. U.S. Pat. Nos. 4,893,671 and 4,991,645 to Legally disclose specific arrangements for anti-vibration bars used in a bundle of U-shaped tubes in a steam generator, in which mating pairs of bars utilize either relative movement of bar halves or quarter-turn rotation of rectangular-shaped bars to increase the effective width of the bar. However, because such known anti-vibration bar configurations are complicated and somewhat unreliable, further needed improvements have been sought and are being provided by the present invention. Also, U.S. Pat. No. 4,637,436 to Stewart, Jr. et al discloses an annular tube-like driver formed of a shape-memory alloy for insertion into a tube to plug the tube. However, the prior art evidently has not provided tube spacers formed of shape-memory metal alloy materials which expand at particular operating temperatures and thereby load and dampen vibrations of tubes in heat exchanger.